A telecommunications system, such as a distributed antenna system (“DAS”), can provide signal coverage to coverage zones in which wireless devices are located. Signals communicated via a DAS or other telecommunications system can include signal components, such as passive intermodulation (“PIM”) products or other intermodulation products, that distort the signals being communicated. Intermodulation products can result from the undesired mixing of signals in a telecommunications system. Intermodulation products can be generated from two tones at different frequencies (e.g., f1 and f2) encountering a non-linear discontinuity or other non-linear interface in a telecommunications system. Examples of a non-linear discontinuity or other non-linear interfaces can include junctions of dissimilar metals in components of a signal path, such as the connections between an antenna and a transmitter. The intermodulation products can include signals having frequencies that are related to the frequencies of the original tones by the relationship
            f      n        =                                        n            +            1                    2                ⁢                  f          1                    -                                    n            -            1                    2                ⁢                  f          2                      ,where n=±3, ±5, ±7 . . . and is the order of the intermodulation product, f1 is the frequency of the lower tone and f2 is the frequency of the higher tone. For example, f3=2×f1−f2 and is the frequency of a third order intermodulation product at a frequency below the frequencies of the two tones. Additionally, f−3=2×f2−f1 and is the frequency of a third order intermodulation product at a frequency above the frequencies of the two tones. The presence of these intermodulation products can indicate that intermodulation is present in the telecommunications subsystem.
A PIM measurement device that is not integral to or otherwise integrated with a telecommunications system can be used to measure PIM products of individual system components before installing each component in the system. This solution does not, however, allow for detecting and measuring the PIM products of an operational telecommunications system once the individual system components have been installed.
Accordingly, it is desirable to detect and measure intermodulation products in a telecommunications system subsequent to installation.